1. Field
Aspects of the invention relate to image processing, and more particularly, to systems, methods and apparatus configured to decimate the output of an image sensor that uses a color filter to discriminate colors.
2. Description of the Related Technology
An image sensor system converts an optical image into a set electrical values representative of the optical image. The electrical values are referred to as electronic image data and can be stored in various file formats. The conversion of an optical image into electronic image data is often accomplished in two broadly defined stages. First, light associated with an optical image is converted into a set of raw analog electrical values by an image sensor. Second, the raw analog electrical values produced by the image sensor are converted into digital values by an analog-to-digital converter to enable digital processing and reconstruction of the electronic image data.
An image sensor typically includes a two-dimensional photosite array, which is also referred to as a pixel sensor array. Each photosite or pixel sensor is used to convert the light associated with a portion of an optical image into a corresponding raw analog electrical value. To that end, each photosite includes at least one photoelectric device that converts incident light into a corresponding raw analog electrical value. Charge-coupled devices (CCD) and complementary metal oxide semiconductor (CMOS) photo sensors are commonly employed in the photosites of image sensors included in consumer products such as digital cameras.
To facilitate color image sensing, an image sensor may include a color filter array that is arranged in combination with a photosite array. In one implementation, a color filter array, such as a Bayer filter, is utilized to selectively pass one of red, green, or blue light to each photosite in accordance with a particular filter pattern. The combination of the color filter array and the photosite array form an array of three interlaced grids, each of which is sensitive to one of red, green, or blue light. In operation, a single color is sampled at each photosite because each photosite is sensitive to one of red, green, or blue light. Employing this configuration a single photosite cannot fully determine a spectrum of color alone because each photosite is individually configured to capture only one of three colors. To obtain a full-color image a demosaicing algorithm is typically used to interpolate a set of complete red, green, and blue values for each point of an image. In other words, a color image is estimated by interpolating the three interlaced grids.